1. Field of the Invention
The present invention relates to a method of polishing a workpiece by pressing the workpiece against a pad while supplying a slurry to a top surface of the pad, and a polishing system therefor.
2. Related Art
In a chemical mechanical polishing (CMP), while a slurry is supplied onto a polishing pad and a turntable is rotated, a workpiece is polished. The pH value or the like of the slurry before polishing can be detected by measuring a state of a supply tank of the slurry. When the slurry is supplied onto the polishing pad to carry out polishing, polishing speed and polishing quality varies with the concentration, pH value, flow rate or the like of the slurry supplied onto the polishing pad. Besides, when plural kinds of slurries are mixed to carry out polishing, the polishing speed or polishing quality varies with a mixed degree of the slurries.
To directly monitor the characteristics of the slurry during polishing, a measuring device has to be placed in the vicinity of the polishing pad. However, conventionally, there has been no proposed practical means which can monitor the characteristics without suspending a polishing process. To measure the characteristics of the slurry during polishing without affecting the polishing process, a dedicated measuring device has to be developed, which increases a production cost. Furthermore, a certain space has to be provided for installation of the dedicated measuring device, which may reduce the productivity.